Improvement in casting pulleys



2Sheets--Sheet I.

J. M U BDU GK.

Casting Pulleys.

Patented Aug. 17,1875.

Mi names. NI\\\Q\ N ETERS. PMOTOJJT R, WASHINGT 2 Sheets--Sheet 2.

.I. MUBDOBK.

Casting Pulleys.

N0.166,799, Patented Au g17,l875.

W names In'vcnior,

MPETERS. PHOTO-LIIHDGRAFHER. WASHINGTON. D G.

UNITED STATES PATENT OFFICE.

JOHN MURDOGK, OF CARVER, MASSACHUSETTS.

IMPROVEMENT IN CAS TING PULLEYS.

Specification forming part of Letters Patent No. 166,799, dated August17, 1875; application filed April 17, 1874.

7 structing the pattern for molding such pulleys;

second, in the pulley so made as a new manufacture; and, third, in amode of securing such pulleys to their shafts.

In making cast-iron pulleys in the usual way, in which a singleset ofarms is used,

which are placed in the middle of the length of the pulley, and ofsuflicient strength to support the strain, and are attached to a hub attheir inner ends, it is difficult to prevent the breaking of the arms ordistorting the rim by reason of the unequal cooling and contraction ofthe parts, as is well understood by foundrymen, and to avoid thisvarious expedients-are resorted to, such as making-the arms of such formas to allow them to yield to the strain without breaking in cooling,allowing the pulley to cool in the sand, so as to make the cooling moreuniform, or uncovering the hub of the pulley as soon as the metal is setby removing the sand from the hub to hasten its cooling, while the restof the casting remains buried, with other analogous practices toaccomplish the same purpose; but by my mode of operation most of thoseexpedients are unnecessary.

The distinguishing characteristics of my invention are, first, that thepulley is made with two sets of thin arms, each set being placed at ornear each edge of the rim, and connected to the other at the center by athin hub, so that the thickness of the metal in the pulley is nearly thesame in all parts, and in all parts much thinner than would be safe inpulleys as usually made, which is accomplished by the use of two sets ofarms placed at each end of the pulley, and making the hub connectingthem thin, so that the rate of shrinkage in all parts is nearlyuniform,-and the castings can entirely in green sand, and without thenecessity of using any core-work; and, third, by the use of such a thinhub to the pulley some further provision is necessary to fasten the sameto the shaft when it is desired to do this by set-screws, because themetalin the hub is not thick enough to form asuflicient nut for thescrews, and for this purpose the hub is made of such shape as to formrecesses upon the inside to receive bar-nuts, through which theset-screws work, and which nuts are made to bear against the inside ofthe hub close to the arms, so that the strain of the screws is receivedat the part of the hub which is strong enough to withstand it.

In the drawings, Figure lis a section through the middle of the pulley,showing the fastenings. Fig. 2 is a section at a right angle to Fig. 1.Fig. 3 is an inside elevation of onehalf of the pattern made'with a hubsuitable for a loose pulley, where a chamber is made in the hub for alining of soft metal for a wearing-surface. Fig. 4 is a section throughthe mold and pattern, showing the method of molding the same. Figs. 5and 6 are two detached views of the bar-nuts and set-screws ,upon theback side in relation to the recesses that they bear against theinterior of them out to the ends, as seen in Fig. 2, and nearly underthe arm. The bosses B on the nuts, which secure the set-screws 0, passthrough holes which are cast in the shell of the hub, as shown. D D arethe arms, made of any desired form, but thin, and, by preference, ofcurved crosssection, as shown by the crosssection at d, Fig. 1, by whichthe armsare made much stronger laterally without a material increase inthe weight. Bis the rim of the pulley, made of nearly uniform thicknessthroughout, with the draft upon the inside, made in the oppositedirection from that usually made, as well as that of the hub The mode ofconstructing the pattern and of molding the same is shown in Fig. 4, inwhich F and G are the two parts of an iron flask, and H and H are thetwo parts of the pattern. I and 1 are the cope and nowel of the mold. J

is the middle part within the pattern, and J 2 the parts J and J areconnected through the holes in the hub, and form one piece. The draftsof the pattern are made so'th'at the'two' parts draw away from theparting instead of toward it, as is usual.

In molding this pattern the method of pro cedure is as follows: One-halfof the pattern is laid upon the molding-board, outside down, and rammedup inside, and stricken off, and then turned over upon a plainmolding-board. The parting-surface at the face of the arms is finished,and parting-sand applied. Then one part of the flask is put over itandrammed up; then it is turned over, and the face isfinished outside ofthe pattern; then the other half of the pattern is put on, and theinside is rammed up uniting the sand with that in the other part of thepattern, and finished at the arms; then the parting-sand is applied tothe whole surface; then the other part of the flask" is put on, andrammed up. To draw the pattern the cope is lifted off down to the middleparting, and one-half of the pattern is then drawn; then the cope isreplaced, and the whole mold turned over; then the other part of themold is lifted off, and the other part of those in common use.

joined tothe'rim" at or near its ed'ge's, an'd to each other by a thinhub, as a new manufacture. v

The recesses in the hub, in combination with th'e detachedvnuts' andset-screws, substantially as described.

Executed April 11, 1874.

V JOHN MURDOOK. Witnesses! WM. P. ED ARDS,

